The present invention relates to a silicone rubber that can be bonded directly to synthetic resins or metallic base members; a composite structure in which a silicone rubber and a base member are bonded; a denture integrally lined with silicone rubber on a section of a denture base where it contacts a body; and a method for making a denture.
Denture users experience an extremely unpleasant sensation when they bite hard food. Furthermore, unstable dentures can make eating, talking, and the like difficult. The denture base that presses against the oral cavity mucosa is a hard resin formed from methyl polymethacrylate. Slight gaps form between the denture base and the oral cavity mucosa even if the dentures have been produced using a precise mold formed in the shape of the denture wearer""s mouth. The gaps form because of the lack of sufficient precision when making the dentures.
Various types of denture stabilizers have been marketed. A significant number of denture wearers purchase and use denture stabilizers that are applied to the contact surface between the mouth and the denture base. The pain resulting from biting hard food is reduced or eliminated by using these dentures stabilizers, and the dentures are more comfortable to wear. However, these effects last only four or five days at most. This method is expensive and time-consuming for the denture wearer.
Another technique is the adhesion using a solvent of a polyvinyl silicone resin-based liner to the section of the denture base that contacts the body. MOLOPLAST(trademark) from Detax Corp., SOFTLINER(trademark) from GC Corp., and SOFRELINER(trademark) from Tokuyama-Dental Corp. are examples of this type of dental technology.
However, the polyvinyl silicone resin-based liner has a Shore hardness of 30-80 and is relatively hard. Pain from biting hard food using dentures with a liner is lower than the pain from biting hard food using dentures with no liner. However, the dentures with a liner are neither comfortable nor stable. Furthermore, the liners described above show rapid discoloration, rapid degeneration, and weak adhesive strength. Thus, the lifespan of the dentures with a liner is a few months to approximately five years and is relatively short. Therefore, the dentures with a liner are expensive for the denture wearer since they must be replaced frequently.
Another type of denture lining is formed with biocompatible silicone rubber, which is used for synthetic biological materials and prosthetics. These dentures are physiologically similar to the oral mucous membrane, reduce the pain from biting hard food, and are not loose. However, there are no adhesives that can bond biocompatible silicone rubber with a denture base of synthetic resin. Sufficient bonding strength and durability is difficult to obtain. Thus, dentures with linings formed with biocompatible silicone rubber, with the exception of the present invention, have not been implemented.
Adhesive agents have been made in which different types of additives are added to silicone gels. However, there is no conventional method for integrally forming a polymer, such as methyl polymethacylate, having good adhesive properties on the surface of silicone rubber.
The present invention provides a silicone rubber with improved adhesive qualities for denture bases or other base members made of synthetic resin or metal; a composite structure of silicone rubber and a base member in which silicone rubber is bonded firmly to the base member described above; a denture in which silicone rubber serves as a denture liner that is firmly bonded to the denture base; and a method for making dentures in which silicone rubber serves as a denture liner that is firmly bonded to the denture base.
The silicone rubber of the present invention is formed by adding methyl methacrylate to a linear polysiloxane and polymerizing. The linear polysiloxane is expressed by the following chemical equation: 
where (m+n=50-2000). Polymerization can be achieved by adding a cross-linking agent such as hydrogen polysiloxane, if necessary.
Silicone-silicone polymerization, silicone-methyl methacrylate polymerization, methyl methacrylate-methyl methacrylate polymerization, and the like take place in the polymerization reaction described above and form a silicone rubber. Methyl polymethacrylate, which adheres strongly to objects, is formed at least on the surface of this silicone rubber. The polymerization reactions can take place in a predetermined container or mold. Alternatively, the reactions can take place in contact with the surface of the synthetic resin or metal base member to which the silicone rubber is to be bonded.
A silicone rubber-base member composite structure according to the present invention is made using a linear polysiloxane as described above. A monomer, such as a methyl methacrylate, is added to the linear polysiloxane described above, and a polymerization reaction takes place with the silicone to form the silicone rubber which is directly bonded to a synthetic resin or metal base member.
A denture according to the present invention includes a denture base, which is the base member in the composite structure described above. A silicone rubber similar to the silicone rubber in the composite structure described above lines a section of the denture base mounted in the body. The silicone rubber can be a biocompatible silicone rubber, and the monomer can be methyl methacrylate.
A method for making dentures according to the present invention includes a method for making dentures in which the silicone rubber described above is bonded to a newly formed denture and a method for making dentures in which the silicone rubber described above is bonded to an existing denture.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.